1. Field of the Invention
The present invention relates to a light emitter substrate and an image displaying apparatus which uses the light emitter substrate.
2. Description of the Related Art
Conventionally, an image displaying apparatus which comprises a rear plate substrate having plural electron-emitting devices arranged in matrix and a light emitter substrate having plural light emitting members arranged in matrix and opposed to the plural electron-emitting devices has been known. In the image displaying apparatus like this, the light emitter substrate and the rear plate substrate are typically opposed to each other at a gap of about several millimeters, and high voltage of, e.g., approximately 10 kV is applied between these substrates. For these reasons, a discharge occurs easily, and, if the discharge once occurs, a discharging current flows from the whole of a metal back which has been integrally formed, whereby an influence to the electron-emitting devices expands.
Consequently, in order to allow the image displaying apparatus of the above type to have a discharging current control function, Japanese Patent Application Laid-Open No. 2006-173094 corresponding to U.S. Patent Application Publication No. US-2006-0103294 (called a patent document 1 hereinafter) and Japanese Patent Application Laid-Open No. 2006-185632 corresponding to European Patent Application Publication EP-A-11830379 (called a patent document 2 hereinafter) respectively disclose techniques for controlling a discharging current by two-dimensionally dividing a metal back and establishing a connection between the divided metal backs by a resistor.
However, if a discharge occurs in a case where further high voltage is applied to improve luminance, a potential difference between the adjacent metal backs increases, whereby there is a possibility that a secondary discharge occurs between the adjacent metal backs. Besides, if the resistor is arranged between the adjacent metal backs, withstand voltage of a material of the resistor is lower than surface withstand voltage between the metal backs according to a kind of the relevant material, whereby there is a possibility that withstand discharge structure is destroyed. In particular, in an ordinary image displaying apparatus to be used for a TV monitor, since a distance between the metal backs adjacent in a horizontal direction (=a row direction) is small, the secondary discharge occurs easily. If the secondary discharge occurs, the discharging current increases, whereby there is a possibility that a damage such as device destruction or the like which is not preferable for image displaying occurs.
To cope with such a problem as described above, in the patent document 1 and the patent document 2, it is designed to define resistance in the row direction without arranging any resistor between light emitting members adjacent in the row direction. More specifically, the patent document 1 discloses the structure that the metal back divided in matrix and the resistors patterned in matrix are combined, and any resistor is not arranged between the metal backs adjacent in the row direction. Further, the patent document 2 discloses the structure that the metal backs divided in matrix and striped resistors expanding in the row direction between the metal backs adjacent in a column direction are connected on the column side of the light emitting members.
However, in the light emitter substrate disclosed in the patent document 1, further improvement is desired in the points of definition of the resistance of the resistor and the withstand voltage of the material. Also, in the light emitter substrate disclosed in the patent document 2, structure of further weakening field intensity applied to the resistor by controlling the secondary discharge between the metal backs adjacent in the row direction is desired.